Microwave-assisted synthesis of copper oxide nanoparticles using an Andrographis paniculata leaf extract: Characterization and multifunctional biological activities

This research delves into the environmentally friendly production of copper nanoparticles (CuNPs) using Andrographis paniculata leaf extract (Ap-CuNPs) and their thorough assessment for possible biological purposes. CuNPs were synthesised through a microwave-assisted method using Andrographis paniculata leaf extract. Characterization techniques included ultraviolet spectroscopy (UVVis), FT-IR spectroscopy, SEM, EDAX, XRD, particle size analysis, and zeta potential measurement. Biological activities were assessed through antioxidant (DPPH and H₂O₂ assays), anti-inflammatory (BSA and egg albumin denaturation assays), antimicrobial, cytotoxic (brine shrimp lethality and MTT assays), and wound healing (scratch assay) tests. Characterization confirmed the formation of Ap-CuNPs with a plasmon resonance peak at 550 nm, the presence of phytochemical capping agents, and high crystallinity. The average particle size was 69.1 nm, with a zeta potential of −12.1 mV. Ap-CuNPs exhibited significant antioxidant activity, with 88.62 % inhibition in the DPPH assay, in the H₂O₂ assay, which assesses the capacity to scavenge hydrogen peroxide, the Ap-CuNPs achieved 86.3 % inhibition at the same concentration. and anti-inflammatory activity, with 80 % inhibition in the BSA assay. Antimicrobial tests revealed strong activity against gram-negative bacteria in the 22 mm inhibition zone for Pseudomonas sp., for S. aureus, the inhibition zones were 9 mm. Cytotoxicity assessments revealed minimal effects at low concentrations, with 200 μg/ml identified as the optimal dose for wound healing. In vitro wound scratch assays demonstrated enhanced fibroblast migration and wound closure at this concentration.